My friend and I took our boys to this movie and both enjoyed it. My son kept pulling my hands up over his eyes, but I don't think he was frightened. In fact, he kept making dragon noises when he ate his popcorn.
I think I enjoyed it just as much as they did! Some of the story, just like other animated movies, has "adult" funny lines thrown in.
If it passes the 3-4 yo test, it must be good (he sat in his seat the entire movie)